1. Field of the Invention
The invention relates to an adjustable-height chair column, comprising an upright tube with a central longitudinal axis; a gas spring, which is disposed in the upright tube coaxially of the central longitudinal axis, and which comprises a casing that is filled with pressure fluid and displaceable in a direction of the central longitudinal axis into an extended position, a piston rod that is fixed in the upright tube, a piston that is mounted on the piston rod, dividing the casing into a first sectional casing chamber and a second sectional casing chamber the piston rod passes through, and a valve for interconnection of the first and second sectional chamber which comprises a valve gate with a valve throat that is coaxial of the central longitudinal axis, a valve pin that is disposed in the valve throat for displacement in a direction towards the first sectional casing chamber into a position of opening, having a blocking element, and a seal that, in a shut-off condition of the valve and upon load on the casing in relation to the upright tube, seals between the blocking element and the valve body.
2. Background Art
In an adjustable-height chair column of the generic type known from U.S. Pat. No. 5,806,828, the basic problem has been solved, which consists in restoring the seat in its elevated position upon relief of the chair column i.e., upon relief of the seat. A need of doing so may for instance occur in meeting-place furniture, in which case there may even be a need for the seats to be restored into a neutral position. The familiar chair column is provided with the conventional valve, by means of which standard height adjustment and control takes place with a user seated on the chair. The piston includes a blocking mechanism of automatic action which opens when the casing is relieved in relation to the upright tube. This known design is comparatively complicated.